Door Security

Some education institutions have replaced key-card entry systems for staff members with a biometric system that uses finger scanning.

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The massacre last year of students and teachers inside Sandy Hook Elementary School in Newtown, Conn., has prompted school systems throughout the nation to re-assess how effectively the doors in their facilities are able to keep intruders out and protect those inside.

Although upgrading school doors won’t necessarily prevent a determined intruder from getting inside a facility, installing equipment that hinders or delays an intrusion may dissuade someone from carrying out an attack or give emergency responders enough time to disrupt it.

In recent years, more focus is being put on providing classroom doors that can be locked from the inside to protect teachers and their students from intruders who may have entered the building and are looking for potential victims.

In California, a law that went into effect in 2011 requires that new K-12 school construction projects that receive state funding “shall include locks that allow doors to classrooms and any room with an occupancy of five or more persons to be locked from the inside.” The law exempts doors to student restrooms and doors that are locked from the outside at all times (examples include storage rooms, janitor’s closets and boiler rooms).

The new requirement for doors does not change the existing provision that classroom doors must be “readily openable from the egress side without the use of a key or special knowledge or effort.”

•Installing annunciator panels that provide visual or audible warnings when a exterior door has been left open.

•Replacing a key-card entry system for staff member with a biometric system that uses finger scanning.

•Installing bullet-resistant film on exterior doors.

Less life-threatening than an armed intruder, but more likely to occur at an education facility is vandalism. To deter someone from breaking into a school, exterior doors should have as little exposed hardware as possible, and their hinges should have non-removable pins, according an assessment guide for schools compiled by the National Clearinghouse for Educational Facilities.

Exterior doors used only for exiting a building do not need handles or locks protruding on the outside, the guide says, but there should be a way, such as a proximity card, to open the door from the outside in an emergency.

Panic bar latches on exterior doors should have pick plates that prevent intruders from using tools or plastic bars to release the bolt, the guide says.

Bullet resistant glass is a glass typically made of a strong, transparent material that gives it the ability to withstand being struck by bullets. Naturally, it is not totally impenetrable. However, instead of shattering it can flex. Bullet resistant glass has many different names. One might call it bulletproof glass, transparent armor, or ballistic glass. What is bullet resistant glass used for? Well, it has more uses than one would imagine. These days, advanced means of protection as well as civil and military means of defense are becoming increasingly important for our safety. For example, several uses of bullet resistant glass include: glass panes for shopping centers, stores, banks, schools, residential buildings, embassies, etc.; as well as for armored vehicles, military and civilian alike.

Bullet Resistant Glass: How Is It Made?

Plastic itself is not bullet resistant, but when put in between layers of glass, it deforms and absorbs the bullet’s energy and thus helps in preventing it from penetrating the glass – stooping it before it goes out the other side.

In order to withstand the massive force bullets can confer on it, bullet resistant glass has gone through an evolution of different materials and methods for the purpose of perfecting it. It is most commonly made of laminated glass arranged in layers, thermoplastic and polycarbonate. The polycarbonate or plastic are layered between sheets of standard glass; this process is called lamination.

The challenge in constructing bullet resistant glass is to make it as transparent and clear as regular glass while stilllensuring that its protective qualities are effective. Bullet resistant glass made with polycarbonate usually incorporates types of polycarbonate sheets such as Lexon, Tuffak, Makroclear, etc. between layers of standard glass. However, the glass itself also undergoes processes to make it stronger, namely, tempering. In tempering, the glass undergoes chemical processes or is treated with cooling and heating that strengthen it.

Plastic also serves as a key material in bullet resistant glass. Plastic itself is not bullet resistant, but when put in between layers of glass, it deforms and absorbs the bullet’s energy and thus helps in preventing it from penetrating the glass – stooping it before it goes out the other side. Other materials used in the making of bullet resistant glass are ethylene vinyl acetate, polyvinyl butyral and polyurethane. Bullet resistant glass made with these materials is usually used in military vehicles and tends to be very thick and heavy.

The Properties of Bullet Resistant Glass

In terms of thickness, bullet proof glass is usually 70 to75 millimetersthick. The thicker it is, the more resistant it is considered to be. Glasses of different thicknesses are needed to withstand penetration from different types of bullets. For example, a handgun bullet wouldn’t strike with the same force as a rifle bullet; therefore, a glass that is meant to withstand rifle bullets should be thicker.

Bullet resistant glass can be affected by environmental factors such as UV radiation from the sun, temperature and exposure to certain solvents. For example, below zero temperatures can sometimes cause the creation of spall – small pieces that break off the polycarbonate. Polycarbonate can be affected by UV radiation as well – however, as long as it is under a layer of glass, it will be protected and not suffer consequences from exposure.

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